#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using System;
using System.Collections;
using log4net.Util;

#if NETCF
using Stack = log4net.Util.ThreadContextStack.Stack;
#endif

namespace log4net {
  /// <summary>
  /// Implementation of Nested Diagnostic Contexts.
  /// </summary>
  /// <remarks>
  /// <note>
  /// <para>
  /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
  /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
  /// </para>
  /// </note>
  /// <para>
  /// A Nested Diagnostic Context, or NDC in short, is an instrument
  /// to distinguish interleaved log output from different sources. Log
  /// output is typically interleaved when a server handles multiple
  /// clients near-simultaneously.
  /// </para>
  /// <para>
  /// Interleaved log output can still be meaningful if each log entry
  /// from different contexts had a distinctive stamp. This is where NDCs
  /// come into play.
  /// </para>
  /// <para>
  /// Note that NDCs are managed on a per thread basis. The NDC class
  /// is made up of static methods that operate on the context of the
  /// calling thread.
  /// </para>
  /// </remarks>
  /// <example>How to push a message into the context
  /// <code lang="C#">
  ///	using(NDC.Push("my context message"))
  ///	{
  ///		... all log calls will have 'my context message' included ...
  ///	
  ///	} // at the end of the using block the message is automatically removed 
  /// </code>
  /// </example>
  /// <threadsafety static="true" instance="true" />
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
  public sealed class NDC {
    #region Private Instance Constructors

    /// <summary>
    /// Initializes a new instance of the <see cref="NDC" /> class. 
    /// </summary>
    /// <remarks>
    /// Uses a private access modifier to prevent instantiation of this class.
    /// </remarks>
    NDC() {}

    #endregion Private Instance Constructors

    #region Public Static Properties

    /// <summary>
    /// Gets the current context depth.
    /// </summary>
    /// <value>The current context depth.</value>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// The number of context values pushed onto the context stack.
    /// </para>
    /// <para>
    /// Used to record the current depth of the context. This can then 
    /// be restored using the <see cref="SetMaxDepth"/> method.
    /// </para>
    /// </remarks>
    /// <seealso cref="SetMaxDepth"/>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static int Depth {
      get { return ThreadContext.Stacks["NDC"].Count; }
    }

    #endregion Public Static Properties

    #region Public Static Methods

    /// <summary>
    /// Clears all the contextual information held on the current thread.
    /// </summary>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// Clears the stack of NDC data held on the current thread.
    /// </para>
    /// </remarks>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static void Clear() {
      ThreadContext.Stacks["NDC"].Clear();
    }

    /// <summary>
    /// Creates a clone of the stack of context information.
    /// </summary>
    /// <returns>A clone of the context info for this thread.</returns>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// The results of this method can be passed to the <see cref="Inherit"/> 
    /// method to allow child threads to inherit the context of their 
    /// parent thread.
    /// </para>
    /// </remarks>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static Stack CloneStack() {
      return ThreadContext.Stacks["NDC"].InternalStack;
    }

    /// <summary>
    /// Inherits the contextual information from another thread.
    /// </summary>
    /// <param name="stack">The context stack to inherit.</param>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// This thread will use the context information from the stack
    /// supplied. This can be used to initialize child threads with
    /// the same contextual information as their parent threads. These
    /// contexts will <b>NOT</b> be shared. Any further contexts that
    /// are pushed onto the stack will not be visible to the other.
    /// Call <see cref="CloneStack"/> to obtain a stack to pass to
    /// this method.
    /// </para>
    /// </remarks>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks", true)]*/
    public static void Inherit(Stack stack) {
      ThreadContext.Stacks["NDC"].InternalStack = stack;
    }

    /// <summary>
    /// Removes the top context from the stack.
    /// </summary>
    /// <returns>
    /// The message in the context that was removed from the top 
    /// of the stack.
    /// </returns>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// Remove the top context from the stack, and return
    /// it to the caller. If the stack is empty then an
    /// empty string (not <c>null</c>) is returned.
    /// </para>
    /// </remarks>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static string Pop() {
      return ThreadContext.Stacks["NDC"].Pop();
    }

    /// <summary>
    /// Pushes a new context message.
    /// </summary>
    /// <param name="message">The new context message.</param>
    /// <returns>
    /// An <see cref="IDisposable"/> that can be used to clean up 
    /// the context stack.
    /// </returns>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// Pushes a new context onto the context stack. An <see cref="IDisposable"/>
    /// is returned that can be used to clean up the context stack. This
    /// can be easily combined with the <c>using</c> keyword to scope the
    /// context.
    /// </para>
    /// </remarks>
    /// <example>Simple example of using the <c>Push</c> method with the <c>using</c> keyword.
    /// <code lang="C#">
    /// using(log4net.NDC.Push("NDC_Message"))
    /// {
    ///		log.Warn("This should have an NDC message");
    ///	}
    /// </code>
    /// </example>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static IDisposable Push(string message) {
      return ThreadContext.Stacks["NDC"].Push(message);
    }

    /// <summary>
    /// Removes the context information for this thread. It is
    /// not required to call this method.
    /// </summary>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// This method is not implemented.
    /// </para>
    /// </remarks>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static void Remove() {}

    /// <summary>
    /// Forces the stack depth to be at most <paramref name="maxDepth"/>.
    /// </summary>
    /// <param name="maxDepth">The maximum depth of the stack</param>
    /// <remarks>
    /// <note>
    /// <para>
    /// The NDC is deprecated and has been replaced by the <see cref="ThreadContext.Stacks"/>.
    /// The current NDC implementation forwards to the <c>ThreadContext.Stacks["NDC"]</c>.
    /// </para>
    /// </note>
    /// <para>
    /// Forces the stack depth to be at most <paramref name="maxDepth"/>.
    /// This may truncate the head of the stack. This only affects the 
    /// stack in the current thread. Also it does not prevent it from
    /// growing, it only sets the maximum depth at the time of the
    /// call. This can be used to return to a known context depth.
    /// </para>
    /// </remarks>
    /*[Obsolete("NDC has been replaced by ThreadContext.Stacks")]*/
    public static void SetMaxDepth(int maxDepth) {
      if (maxDepth >= 0) {
        ThreadContextStack stack = ThreadContext.Stacks["NDC"];

        if (maxDepth == 0)
          stack.Clear();
        else
          while (stack.Count > maxDepth)
            stack.Pop();
      }
    }

    #endregion Public Static Methods
  }
}